Parametric (Bell) Filters; The Controls; Individual Band Controls; Gain - Waves Y56K User Manual

to remain, the target frequencies are still removed and the resulting sound is sweeter and brighter.
N ot e! Steep, brick-wall filters are still applicable to multimedia or other band-limited tasks, such as
N ot e!
digital conversions. The REQ filters are designed for pro audio and other musically demanding
applications.
Bands 1 and 6 are third-order filters (Q=1, 18 dB/octave). When the Q is higher than 1, the notch
and bump yield a higher slope than a third-order filter, but still pass some of the higher harmonics,
although reduced in amplitude. At the lowest Q (0.71), the slope is slightly less than a second-order
filter (10 dB/octave).

Parametric (Bell) Filters

Most people are familiar with the parametric equalizer invented by George Massenberg. The para-
metric filter has three controls: center frequency, bandwidth (or Q), and gain (boost or cut). Almost
without exception, they have symmetrical response characteristics: boost and cut have the same
"bell" shape for a selected bandwidth or Q setting. An asymmetrical filter has a different shape for
boost and cut for the same Q setting.
Since it is common to boost a relatively wide bandwidth for aesthetic tonal correction and cut a nar-
row bandwidth to remove artifacts (i.e., feedback, excessive vocal sibilance), an asymmetrical
response is perhaps more useful in the analog domain. Asymmetrical filters have been described by
several audio researchers and designers (including Mitra, "Hutch" Hutchinson, and others), but not
included in commercial products to our knowledge. Waves chose to include this type of filter simply
because it sounded better for professional use.

The Controls

When the REQ is first inserted, all bands are switched In by default except Band 1, which is intentionally
Out because it is a low-cut filter.

Individual band controls

The small controls beneath the frequency curve display are the Value Windows for Gain, Frequency,
and Q for each band. At the bottom of each column is the control to switch each band In or Out,
and to choose the filter type.
G ain
G ain
The Gain may be adjusted ±18 dB, in increments of 0.1 dB, and is displayed in the frequency
response graph.
F r eq
F r eq
The Frequency control displays the each band's center frequency for parametric filters or the
corner frequency for shelving filters. The Frequency control values are adjustable in 1/96
octave increments, rounded to the closest integer frequency (Hz).
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Y56K User Guide